COMMUNICATIONS
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Experimental Section
Typical Procedure for the Photocatalytic Aerobic
Oxidation of Thiols to Disulfides in Batch
To an oven-dried vial equipped with a magnetic stir bar was
added Eosin Y (6.5 mg, 1 mol%), thiol (1 mmol), and etha-
nol (1 mL). The vial was placed in a test tube rack and irra-
diated by a compact fluorescent light bulb (24W, E-27
240 V Calex Daylight Lamp). The distance between reaction
mixture and the light source is approx. 2 cm. The reaction
was stirred vigorously to increase the contact between the
liquids and air. The progress of the reaction was monitored
using GC-MS and/or TLC. After completion of the reaction,
the solvent was removed under vacuum and the residue was
purified by flash column chromatography.
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Habel, T. Heinekamp, C. Hertweck, A. A. Brakhage,
E. M. Huber, Angew. Chem. 2014, 126, 2253–2256;
Angew. Chem. Int. Ed. 2014, 53, 2221–2224; b) H. T.
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346, 889–900; b) A. N. Gent, Rubber Chem. Technol.
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Zeitler, Angew. Chem. 2009, 121, 9969–9974; Angew.
Chem. Int. Ed. 2009, 48, 9785–9789; b) J. W. Tucker,
C. R. J. Stephenson, J. Org. Chem. 2012, 77, 1617–1722;
c) C. K. Prier, D. A. Rankic, D. W. C. MacMillan,
Chem. Rev. 2013, 113, 5322–5363; d) D. A. Nicewicz,
T. M. Nguyen, ACS Catal. 2014, 4, 355–360; e) D. P.
Hari, B. Konig, Chem. Commun. 2014, 50, 6688–6699.
[8] a) T. Noꢀl, V. Hessel, ChemSusChem 2013, 6, 405–407;
b) P. Sobieszuk, J. Aubin, R. Phorecki, Chem. Eng.
Technol. 2012, 35, 1346–1358; c) A. Gunther, K. F.
Jensen, Lab Chip 2006, 6, 1487–1503.
[9] For reviews pertaining the combination of continuous
flow microreactors and photochemistry: a) Y. Su,
N. J. W. Straathof, V. Hessel, T. Noꢀl, Chem. Eur. J.
2014, 20, 10562–10589; b) Z. J. Garlets, J. D. Nguyen,
C. R. J. Stephenson, Isr. J. Chem. 2014, 54, 351–360;
c) E. M. Schuster, P. Wipf, Isr. J. Chem. 2014, 54, 361–
370; d) T. Noꢀl, X. Wang, V. Hessel, Chim. Oggi 2013,
31, 10–14; e) M. Oelgemoeller, Chem. Eng. Technol.
2012, 35, 1144–1152; f) J. P. Knowles, L. D. Elliott, K. I.
Booker-Milburn, Beilstein J. Org. Chem. 2012, 8, 2025–
2052; g) M. Oelgemoeller, O. Shvydkiv, Molecules
2011, 16, 7522–7550; h) E. E. Coyle, M. Oelgemoeller,
Photochem. Photobiol. Sci. 2008, 7, 1313–1322; i) Y.
Matsushita, T. Ichimura, N. Ohba, S. Kumada, K.
Sakeda, T. Suzuki, H. Tanibata, T. Murata, Pure Appl.
Chem. 2007, 79, 1959–1968.
[10] Selected papers concerning photoredox catalysis in
continuous flow: a) N. J. W. Straathof, B. J. P. Tegel-
beckers, V. Hessel, X. Wang, T. Noꢀl, Chem. Sci. 2014,
5, 4768–4773; b) N. J. W. Straathof, H. P. L. Gemoets,
X. Wang, J. C. Schouten, V. Hessel, T. Noꢀl, ChemSus-
Chem 2014, 7, 1612–1617; c) D. Cantillo, O. de Frutos,
J. A. Rincon, C. Mateos, C. O. Kappe, Org. Lett. 2014,
16, 896–899; d) X. Wang, G. D. Cuny, T. Noꢀl, Angew.
Chem. 2013, 125, 8014–8018; Angew. Chem. Int. Ed.
2013, 52, 7860–7864; e) A. C. Hernandez-Perez, S. K.
Collins, Angew. Chem. 2013, 125, 12928–12932; Angew.
Chem. Int. Ed. 2013, 52, 12696–12700; f) M. Neumann,
K. Zeitler, Org. Lett. 2012, 14, 2658–2661; g) J. W.
Tucker, Y. Zhang, T. F. Jamison, C. R. J. Stephenson,
Angew. Chem. 2012, 124, 4220–4223; Angew. Chem.
Int. Ed. 2012, 51, 4144–4147.
General Procedure for the Photocatalytic Aerobic
Oxidation of Thiols to Disulfides ꢀn Flow
To an oven-dried volumetric flask of 10 mL capacity was
added Eosin
Y (16.2 mg, 1 mol%), thiol (2.5 mmol),
TMEDA (375 mL, 2.5 mmol), and ethanol to make up the
solution to 10 mL. The solution was taken up in a BD Dis-
cardit plastic syringe and introduced into the photomicror-
eactor set-up with a syringe pump. The syringe pump and
mass flow controller were operated at a 1:2 reaction mixtur-
e:oxygen volume flow ratio to obtain a maximum residence
time of 20 min. The progress of the reaction was monitored
using GC-MS and/or TLC. Three residence times were dis-
carded to ensure steady-state data collection. Next, the reac-
tion mixture was collected until 1 mmol of product was ob-
tained. The solvent was removed under vacuum and the res-
idue was purified by flash column chromatography.
Acknowledgements
T.N. would like to acknowledge financial support from the
Dutch Science Foundation for a VENI Grant (No 12464)
and from the European Union for a Marie Curie CIG Grant
(Flach). Funding by the Advanced European Research Coun-
cil (Grant number: 267443 for V.H.) and the Netherlands Or-
ganization for Scientific Research via a Gravity program
(024.001.035) is kindly acknowledged.
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Adv. Synth. Catal. 0000, 000, 0 – 0
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